Despite advances in surgical technique, radiation therapy, and chemotherapy most patients diagnosed with malignant brain tumors will succumb to their disease within one year of the time of diagnosis. Despite many advances in modern medicine, very little is yet known about what causes malignant brain tumors to arise in the first place. One characteristic of brain tumors which scientists have discovered is that they are capable of producing certain substances called growth factors that can stimulate their own growth. It is possible that by blocking the tumor's production of these growth factors that one could slow or stop the growth of the tumor. One such factor is scatter factor/hepatocyte growth factor (SF/HGF). It contributes to tumor growth by stimulating tumor growth, blood vessel formation, promoting tumor invasion. We have developed a novel genetic approach called a U1/ribozyme that inhibits production by tumor cells of SF/HGF and/or its receptor c-met. In this study we will demonstrate that we can deliver this novel therapeutic agent effectively to brain tumors and that we can slow or prevent tumor growth in animal models of brain tumors. Successful completion of these studies will pave the way for clinical trials of this agent for patients suffering from malignant brain tumors.